Basic railroad hopper car structures involve an elongated walled enclosure for holding particulate matter. The walled enclosed is typically mounted on a mobile underframe and the railroad car defines a longitudinal axis. It is well known for the walled enclosure of railroad hopper cars to be divided into a plurality of separated receiving compartments, such as four compartments or any desired number. A bottom of each compartment defined by the walled enclosure is usually provided with a series, typically one or more, of individual discharge openings arranged along and on opposite side of the longitudinal axis and through which particulate matter or ballast, held and transported within the walled enclosure, is to be discharged. Typically, the walled enclosure is provided with a series of slant sheets or slanted walls funneling downwardly toward each discharge opening to facilitate the discharge of the particulate matter from the car.
Various methods and devices are known in the art for individually closing the discharge openings disposed along the bottom of the hopper car. Basically, such closure devices are divisible into two categories. Some hopper cars utilize a sliding gate or valve type device for closing the discharge openings at the bottom of each compartment. Alternatively, some hopper cars are provided with hinged doors for controlling the discharge of particulate matter through the discharge openings.
A conventional slide gate device includes a frame which is bolted or otherwise secured to the hopper car. The frame defines a discharge opening arranged in operative combination with an opening at the bottom of the slanting walls on the hopper car. A gate is arranged on the frame for sliding movement between open and closed positions relative to a respective discharge opening. When open, the sliding gate permits the contents of the hopper car enclosure to pass gravitationally through the discharge opening defined by the frame of the gate assembly. When closed, the sliding gate shuts off the material or matter flow through the gate. Typically, the gate is driven between positions by imparting rotary movement to a rotatable operating shaft assembly. As will be appreciated by those skilled in the art, opposite ends of the operating shaft assembly are engagable by a power driven tool to forcibly move the gate between positions.
Although widely used throughout the railroad industry, conventional slide gate mechanisms require intense manual effort during an unloading operation. Moreover, the capability to quickly discharge materials through the opening in the frame of the gate assembly is somewhat limited with slide gate mechanisms. Accordingly, slide gate mechanisms are limited in their applications and uses
Alternatively, hinged doors on other forms of railroad hopper cars are generally larger in size compared to the gate size afforded by slide gate mechanisms. As is well known in the art, the hinged doors are moved from their closed position to an open position by gravity upon the release of a locking mechanism. These hinged doors typically include an elongated generally flat steel plate which is hinged toward its upper edge or side to the hopper car. Various devices are known in the art for forcibly returning the doors from their open position to their closed position or condition.
In many railroad hopper cars, such doors are mounted transversely relative to a longitudinal axis of the railroad car. Research has revealed, however, transversely arranged doors on a railroad car offer a limited throat area through which material or ballast is discharged from the car.
Because of their larger size, the hinged doors on the hopper car have increased load levels placed thereon by the commodity held within the walled enclosure. The individual locking mechanisms typically provided in combination with and for holding the each door on the car in a releasably closed position includes components which are normally pushed during an unlocking operation. Thus, the component parts of each locking mechanism must be designed to not only withstand the increased load levels placed thereon by the ballast within the hopper but also the increased forces inherent with devices which are pushed rather than pulled. Notwithstanding the increased load levels placed thereupon, the locking mechanism for releasably holding the hinged door of a railroad hopper car in a closed position must operate with conciseness while maintaining sufficient strength and durability to sustain its continued operation in changing environments.
As will be appreciated by those skilled in the art, and as the railroad hopper car is transported across the country between destinations, the locking mechanism for releasably holding the side door of the hopper car in a closed position is subjected to dirt, dust, wetness, corrosion and a variety of changing environments. Yet, when the hopper car arrives at an unloading site, the locking mechanism is expected to operate in a manner permitting quick and easy unloading of the compartments of the hopper car.
Thus, there is a need and a desire for a positively operated locking mechanism for maintaining a hinged side door of a railroad hopper car in a releasably and locked closed position notwithstanding the environment and those inherent problems and rigid performance criteria associated with railroad hopper cars mentioned above.